W272 
This species has been found to be widely distributed. I have seen examples obtained 
from the deep water of the Farée Channel. 
5. Metridia venusta Giesbrecht. Plate XXXVII, figs. 15—20. 
Metridia venusta Giesbrecht, 1889, p. 24. 
Metridia venusta Giesbrecht, 1893, p. 340, pl. 33 (female). 
Metridia normant Giesbrecht, 1893, p. 340, pl. 33 (male). 
Metridia venusta Giesbrecht & Schmeil, 1898, p. 107. 
Metridia normant Giesbrecht & Schmeil, 1898, p. 107. 
Metridia normant Wolfenden, 1904, p. 125, pl. IX, fig. 39. 
Metridia venusta Cleve, 1904, p. 192. 
Metridia venusta Farran, 1905, p. 43. 
Metridia venusta Pearson, 1906, p. 23. 
Metridia venusta Farran, 1908, p. 60. 
Metridia venusta van Breemen, 1908, p. 110, fig. 126. 
Metridia normant van Breemen, 1908, p. 109, fig. 125. 
Twelve females and six males belonging to the above species were found in the plankton 
collected, with one exception, by means of the HENsEN vertical net at the following stations. 
Stat. 118 (900 metres to surface), 2 specimens. — Stat. 128 (700 metres to surface), 3 spe- 
cimens. — Stat. 141 (1500 metres to surface), 3 specimens. — Stat. 142, I specimen. — 
Stat. 143 (1000 metres to surface), 4 specimens. — Stat. 148 (1000 metres to surface), 
2 specimens. — Stat. 203 (1500 metres to surface), 2 specimens. — Stat. 276 (750 metres 
to surface), I specimen. 
The two sexes of this J/etrzdza can readily be recognised by the asymmetrical furcal 
joints. The right furcal joint is distinctly shorter than the left. The fifth pair of feet of the 
female, consists of one free joint attached to a basal part. Length, female 3,1, male 2,8 mm. 
I do not think that there can now be any doubt that the species described by G1rsBRECHT 
as Metridia normant, is only the male of Metrzdza venusta. The male fifth pair illustrated in 
this report is identical with the figure given by GresprecHT. WOLFENDEN’s figure of the fifth 
pair of the supposed female of M/etrzdia normani is simply the fifth pair of the female of 
Metridia venusta. If a line be drawn across from the outer edge setae to the inner margin 
in the figure now given, one would practically have a similar illustration to that shewn by 
WoLFENDEN. The joint shewn by that author is probably due to a defective preparation. 
GIESBRECHT’s figure of the female fifth pair, shews the apex of the free joint to be furnished 
with two setae. The ‘Siboga’ females have three as illustrated. (Plate XXXVI, fig. 17). 
Metridia venusta has a distribution almost similar to that of A/etrzdia princeps. 
Genus Pleuromamma Giesbrecht, 1898. 
The members of this genus are readily recognised by the presence of a pigmented 
luminous organ on the right or left side of the first thoracic segment. 
Three species were represented in the area traversed by the ‘Siboga’. 
1. Pleuromamma abdoninalis (Lubbock). 
Diaptomus abdominalis Lubbock, 1856, p. 22, pl. X. 
122 
